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Mass air flow issue

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Trinity-27

Probationary Member
28
0
Dec 22, 2016
Suquamish, Washington
So i bought a 97 gsx with a 6 bolt swap and it blew up first time i started it never even made it out od the driveway, so i conpletely rebuikt the engine with new block new valves gaurds and seals, oem crank, manley h beam rods, weisco 8.3 to 1 compression pistons, acl race bearings oem oil pump new oem timing belt and pulleys, mitsubishi balance shaft stub as i removed the balance shafts, cometic headgasket, topline gasket kit and head bolts, arp main bolts and studs, and put the engine together and dropped it in and it cant stay running unless the mass air flow sensor is unplugged, and when it is it runs in "limp mode" where it runs super rich and cant get past 3500 rpms in neutral, and around 2 under its own weight. I replaced the maf with one from oreilys and that didnt fix the issue it still cant even idle with the maf plugged in. Does anyone have any advice what could cause this? Im faily certain its an electrical issue, i did take the ecm (engine control module) from a 91 gs could it be that is somehow throwing the engine off? The check engine light only comes on when i have the maf unplugged and thats because its unplugged. Any help or ideas would be greatly appreciated ive put alot of worm and money into this and i feel like im super close but i still cant drive it. Thanks for any help!
 
I'm almost certain that a 1G ECU cannot work with a 2G MAF unless tuned. Also you say GS, so you got a non-turbo ECU like Vegas_Smith says? Find the correct 2G ECU for your car and slap it on if you can.
 
It's not even possible to use a 1g ecu . The plugs are different. We need a run down on what's what.
And no surprise you have no profile.
What injectors are in the car?
Verify what ecu.
Verify mechanical timing.
You've done something very wrong and throwing parts at it isn't a very good solution.
More info please and fill out a profile so we can help you.
 
I'm almost certain that a 1G ECU cannot work with a 2G MAF unless tuned. Also you say GS, so you got a non-turbo ECU like Vegas_Smith says? Find the correct 2G ECU for your car and slap it on if you can.

You can use a 2g maf on a 1g with 550/560 injectors and it will almost cancel each other out. Some use an safc to fine tune it a little more but it's not necessary for it to run and drive.
 
No im using the 2g ecu but im using a 1g power transistor that i tool from a non turbo, would that make any difference from the 1g to 2g? i have the stock 450cc injectors and i believe the ecm is a blackbox or at least i was told it is by the p.o. the timing is correct i made sure and i used a timing light and made sure to do thr cam/crank angle sensor right

Also alot of thr wiring is hacked up from the p.o. theres alot of random spliced wires and weird stuff such as my radiator fan wired so that it comes on whenever i turn on the headlights, as well as a few wires coming off the ecu that arr just cut, since it is 6 bolt swapped and had an a/c delete im assuming most of the hack job wiring is caused by that.
 
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But it runs just really poorly with the maf unplugged and then runs worse with it plugged in what would cause that?
Thanks for the quick replys!
 
The car is not getting the right data from the needed sensors because it's all hacked up. A bit confused about a 1g na ecu on your 2g. Get the right ecu for your car and start there.
It is the 2g ecu i said the wrong thing but what sensor would cause it to go off like that? And should i start by just replacing the wiring harness and going from there?
 
So i took it out and looked at the ecu and its the tuneable ecu from the 98 and 99 gsx but the internals are corroded a bit, i was thinking that could very well be my issue im gonna go to a junkyard in the morning and see if i can get an ecu and or wiring harness
 
There wasnt a 2nd gen dsm at my local junkyard so i ordered an 99 ecu of ebay, and i dont believe my hacked wiring harness is messing with the ecu, because if i unplug the maf it instantly throws a code or two for the maf, and same thing with the other sensors so the wires are making it to the computer i believe, i still want to replace the harness but i dont believe its contributing to my issue. Thanks for the replies and help ill keep you guys informed as i check stuff
 
So i replaced the computer and it runs aloty better and in nuetral it cam rev to 5000 no problem most of the time but occasionaly stutters, but when it is under itd own weight and actually driving it starts to stutter pretty bad and has ignition ping im assuming, where it almost feels like the car hit its rev limiter but its at 2.5 to 3 thousand rpms, and it runs better usually after it gets padt 3.5, i have yet to rev the car past 5000 as it still has less then 200 miles on the rebuild, ive had a few small issues im taking care if now such as my water pump had a bolt come loose and started leaking bad so i went to unbolt it to check it out and it ripped the head off to the threads with little force so in going to have to drill and tap that as well, im assuming the best way to do that would be to take all the motor mounts off except the one on the far passneger side and jack the engine up so i can ger the drill in there? Sorry to type so much and im still not the best with this stuff so thank you all in advance for any help its greatly appreciated. Im assuming its some kind of vacume leak or something air related, would anyone happen to habce a link to all the vacume lines in the 2nd gen dsm and could post that? Again thank you for all the help
 
No im using the 2g ecu but im using a 1g power transistor that i tool from a non turbo, would that make any difference from the 1g to 2g? i have the stock 450cc injectors and i believe the ecm is a blackbox or at least i was told it is by the p.o. the timing is correct i made sure and i used a timing light and made sure to do thr cam/crank angle sensor right

Also alot of thr wiring is hacked up from the p.o. theres alot of random spliced wires and weird stuff such as my radiator fan wired so that it comes on whenever i turn on the headlights, as well as a few wires coming off the ecu that arr just cut, since it is 6 bolt swapped and had an a/c delete im assuming most of the hack job wiring is caused by that.
Random spliced and cut wires? You must fix this. Quit shooting in the dark. Chase the wiring on all critical sensors. From your description there is no other way. You've already described your problem and I understand why you're not going and fixing it
 
I believe all the wires actually make it to the computer that are necessary for the engine to run, being that as soon as i unplug anything it instantly shows a cel that wasnt there and when i check the code it corolates to whatever i unplug, i believe the majority of the random cut wires are from the ac, as well as some wires missing because of the 7 to 6 bolt swap such as the crank sensor is missing. Ive been thinking of just getting a new wiring harness and rewiring it but thats such an intensive solution i want to absolutely make sure that thats the issue. Thanks for the feedback!
 
Also, if it is my wiring harness causing it then this would be related to one single sensor being off, so which sensor would not throw a cel but cause the engine to hit a rev limiter at 3k rpms? I dont believe that is the issue but i will check out the wires and follow them
 
Just because it knows if it is connected or not, does not mean that the signal is clean. Your car is not "hitting a rev limiter" it simply doesn't not have the right information it needs to run at a higher rpm than this. This theory makes sense because adding load into the equation makes it worse.

Do a little bit of work, if you think it is a vacuum leak, find your own line routing chart. If you look hard enough you could find the whole factory service manual. If you really think it is something different than what we are all trying to tell you either 1) Check and double check if you are right to prove either us or you wrong or 2) Stop asking for help.
 
Also, if it is my wiring harness causing it then this would be related to one single sensor being off, so which sensor would not throw a cel but cause the engine to hit a rev limiter at 3k rpms? I dont believe that is the issue but i will check out the wires and follow them
It's really hard to say what's going on as nobody can really look at this wiring mess but you. Your best bet is to really research the ecu pinouts and sensor wiring to truly understand what is connected to what. It's not as hard as you think and you'll be better for doing it.
 
255 walbro fuel pump anf 450cc stock injectors i do have some sort of aftetmarket fuel pressure regulator that lets me manually ajust the amount of pressure it has so i know the fuel pump has pressure
 
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